We present the Haptic Laser, a system for providing a range of tactile sensations to represent a physical environment at-a-distance. The Haptic Laser is a handheld device that simulates interaction with physical surfaces as a user targets objects of interest (e.g., a light switch, TV, etc). Using simple computer vision techniques for scene analysis and laser range finding for calculating distance, the Haptic Laser extracts information about the physical environment and conveys it haptically through a collection of hardware actuators. Pointing the Haptic Laser around a room, for example, presents the user with information about the presence of objects, transitions, and edges through touch rather than, or in addition to, vision. The Haptic Laser extends current work on haptic touch screens and pens, and is designed to allow for haptic feedback from a distance using multiple feedback channels.

Every year, loose objects inside cars during crashes cause hundreds of serious injuries and even deaths. In this paper, we describe findings from a study of 25 cars and drivers, examining the objects present in the car cabin, the reasons for them being there, and driver awareness of the potential dangers of these objects. With an average of 4.3 potentially dangerous loose objects in a car's cabin, our findings suggest that despite being generally aware of potential risks, considerations of convenience, easy access, and lack of in-the-moment awareness lead people to continue to place objects in dangerous locations in cars. Our study highlights opportunities for addressing this problem by tracking and reminding people about loose objects in cars.

We present Portico, a portable system for enabling tangible interaction on and around tablet computers. Two cameras on small foldable arms are positioned above the display to recognize a variety of physical objects placed on or around the tablet. These cameras have a larger field-of-view than the screen, allowing Portico to extend interaction significantly beyond the tablet itself. Our prototype, which uses a 12" tablet, delivers an interaction space six times the size of the tablet screen. Portico thus allows tablets to extend both their sensing capabilities and interaction space without sacrificing portability. We describe the design of our system and present a number of applications that demonstrate Portico's unique capability to track objects. We focus on a number of fun applications that demonstrate how such a device can be used as a low-cost way to create personal surface computing experiences. Finally, we discuss the challenges in supporting tangible interaction beyond the screen and describe possible mechanisms for overcoming them.

We present a study that evaluates the effectiveness of augmenting on-screen instructions with micro-projection for manual task guidance unlike prior work, which replaced screen instructions with alternative modalities (e.g., head-mounted displays). In our study, 30 participants completed 10 trials each of 11 manual tasks chosen to represent a set of common task-components (e.g., cutting, folding) found in many everyday activities such as crafts, cooking, and hobby electronics. Fifteen participants received only on-screen instructions, and 15 received both on-screen and micro-projected instructions. In contrast to prior work, which focused only on whole tasks, our study examines the benefit of augmenting common task instructions. The augmented instructions improved participants' performance overall; however, we show that in certain cases when projected guides and physical objects visually interfered, projected elements caused increased errors. Our results demonstrate that examining effectiveness at an instruction level is both useful and necessary, and provide insight into the design of systems that help users perform everyday tasks.

Anyone within range of an 802.11 wireless network ("Wi-Fi") can use free software to collect the unencrypted web traffic of others on the network. However, many Wi-Fi users are completely unaware of the risk that this creates. This work aims to improve users' awareness about what they expose to others on Wi-Fi networks and provide them with some control. Our system, the Wi-Fi Privacy Ticker, displays information about the exposure of sensitive terms that are sent to and from a user's computer and prevents the unencrypted transmission of terms from the user's computer that she has identified as highly sensitive. In a three-week field study with 17 participants, we found that the Wi-Fi Privacy Ticker improved participants' awareness of the circumstances in which their personal information is transmitted. We show that this heightened awareness contributed to changes in their behavior while on Wi-Fi.

Context-aware intelligent systems employ implicit inputs, and make decisions based on complex rules and machine learning models that are rarely clear to users. Such lack of system intelligibility can lead to loss of user trust, satisfaction and acceptance of these systems. However, automatically providing explanations about a system's decision process can help mitigate this problem. In this paper we present results from a controlled study with over 200 participants in which the effectiveness of different types of explanations was examined. Participants were shown examples of a system's operation along with various automatically generated explanations, and then tested on their understanding of the system. We show, for example, that explanations describing why the system behaved a certain way resulted in better understanding and stronger feelings of trust. Explanations describing why the system did not behave a certain way, resulted in lower understanding yet adequate performance. We discuss implications for the use of our findings in real-world context-aware applications.

We present Bonfire, a self-contained mobile computing system that uses two laptop-mounted laser micro-projectors to project an interactive display space to either side of a laptop keyboard. Coupled with each micro-projector is a camera to enable hand gesture tracking, object recognition, and information transfer within the projected space. Thus, Bonfire is neither a pure laptop system nor a pure tabletop system, but an integration of the two into one new nomadic computing platform. This integration (1) enables observing the periphery and responding appropriately, e.g., to the casual placement of objects within its field of view, (2) enables integration between physical and digital objects via computer vision, (3) provides a horizontal surface in tandem with the usual vertical laptop display, allowing direct pointing and gestures, and (4) enlarges the input/output space to enrich existing applications. We describe Bonfire's architecture, and offer scenarios that highlight Bonfire's advantages. We also include lessons learned and insights for further development and use.

Responsiveness, or the time until a person responds to communication, can affect the dynamics of a conversation as well as participants' perceptions of one another. In this paper, we present a careful examination of responsiveness to instant messaging communication, showing, for example, that work-fragmentation significantly correlates with faster responsiveness. We show also that the presentation of the incoming communication significantly affects responsiveness (even more so than indicators that the communication was ongoing), suggesting the potential for dynamically influencing responsiveness. This work contributes to a better understanding of computer-mediated communication and to the design of new tools for computer-mediated communication.

People have developed a variety of conventions for negotiating face to face interruptions. The physical distribution of teams, however, together with the use of computer mediated communication and awareness systems, fundamentally alters what information is available to a person considering an interruption of a remote collaborator. This paper presents a detailed comparison between self-reports of interruptibility, collected from participants over extended periods in their actual work environment, and estimates of this interruptibility, provided by a second set of participants based on audio and video recordings. Our results identify activities and environmental cues that affect participants' ability to correctly estimate interruptibility. We show, for example, that a closed office door had a significant effect on observers' estimation of interruptibility, but did not have an effect on participants' reports of their own interruptibility. We discuss our findings and their importance for successful design of computer-mediated communication and awareness systems.

A problem with the location-free nature of cell phones is that callers have difficulty predicting receivers' states, leading to inappropriate calls. One promising solution involves helping callers decide when to interrupt by providing them contextual information about receivers. We tested the effectiveness of different kinds of contextual information by measuring the degree of agreement between receivers' desires and callers' decisions. In a simulation, five groups of participants played the role of 'Callers', choosing between making calls or leaving messages, and a sixth group played the role of 'Receivers', choosing between receiving calls or receiving messages. Callers were provided different contextual information about Receivers' locations, their cell phones' ringer state, the presence of others, or no information at all. Callers provided with contextual information made significantly more accurate decisions than those without it. Our results suggest that different contextual information generates different kinds of improvements: more appropriate interruptions or better avoidance of inappropriate interruptions. We discuss the results and implications for practice in the light of other important considerations, such as privacy and technological simplicity.

For the majority of us, inter-personal communication is an essential part of our daily lives. Instant Messaging, or IM, has been growing in popularity for personal and work-related communication. The low cost of sending a message, combined with the limited awareness provided by current IM systems result in messages often arriving at inconvenient or disruptive times. In a step towards solving this problem, we created statistical models that successfully predict responsiveness to incoming instant messages -- simply put: whether the receiver is likely to respond to a message within a certain time period. These models were constructed using a large corpus of real IM interaction collected from 16 participants, including over 90,000 messages. The models we present can

Instant Messaging is a popular medium for both social and work-related communication. In this paper we report an investigation of the effect of interpersonal relationship on underlying basic communication characteristics (such as messaging rate and duration) using a large corpus of instant messages. Our results show that communication characteristics differ significantly for communications between users who are in a work relationship and between users who are in a social relationship. We used our findings to inform the creation of statistical models that predict the relationship between users without the use of message content -- achieving an accuracy of nearly 80% for one such model. We discuss the results of our analyses and potential uses of these models.

The growing use of Instant Messaging for social and work-related communication has created a situation where incoming messages often become a distraction to users while they are performing important tasks. Staying on task at the expense of responsiveness to IM buddies may portray the users as impolite or even rude. Constantly attending to IM, on the other hand, may prevent users from performing tasks efficiently, leaving them frustrated. In this paper we present a tool that augments a commercial IM client by automatically increasing the salience of incoming messages that may deserve immediate attention, helping users decide whether or not to stay on task.

Toolkits and other tools have dramatically reduced the time and technical expertise needed to design and implement graphical user interfaces (GUIs) allowing high-quality, iterative, user-centered design to become a common practice. Unfortunately the generation of functioning prototypes for physical interactive devices as not had similar support -- it still requires substantial time and effort by individuals with highly specialized skills and tools. This creates a divide between a designers' ability to explore form and interactivity of product designs and the ability to iterate on the basis of high fidelity interactive experiences with a functioning prototype. To help overcome this difficulty we have developed the Calder hardware toolkit. Calder is a development environment for rapidly exploring and prototyping functional physical interactive devices. Calder provides a set of reusable small input and output components, and integration into existing interface prototyping environments. These components communicate with a computer using wired and wireless connections. Calder is a tool targeted toward product and interaction designers to aid them in their early design process. In this paper we describe the process of gaining an understanding of the needs and workflow habits of our target users to generate a collection of requirements for such a toolkit. We describe technical challenges imposed by these needs, and the specifics of design and implementation of the toolkit to meet these challenges.

The current practice used in the design of physical interactive products (such as handheld devices), often suffers from a divide between exploration of form and exploration of interactivity. This can be attributed, in part, to the fact that working prototypes are typically expensive, take a long time to manufacture, and require specialized skills and tools not commonly available in design studios. We have designed a prototyping tool that, we believe, can significantly reduce this divide. The tool allows designers to rapidly create functioning, interactive, physical prototypes early in the design process using a collection of wireless input components (buttons, sliders, etc.) and a sketch of form. The input components communicate with Macromedia Director to enable interactivity. We believe that this tool can improve the design practice by: a) Improving the designer's ability to explore both the form and interactivity of the product early in the design process, b) Improving the designer's ability to detect problems that emerge from the combination of the form and the interactivity, c) Improving users' ability to communicate their ideas, needs, frustrations and desires, and d) Improving the client's understanding of the proposed design, resulting in greater involvement and support for the design.

Ordinary paper offers properties of readability, fluidity, flexibility,
cost, and portability that current electronic devices are often hard pressed to
match. In fact, a lofty goal for many interactive systems is to be "as easy to
use as pencil and paper". However, the static nature of paper does not support
a number of capabilities, such as search and hyperlinking that an electronic
device can provide. The Paper PDA project explores ways in which hybrid paper
electronic interfaces can bring some of the capabilities of the electronic
medium to interactions occurring on real paper. Key to this effort is the
invention of on-paper interaction techniques which retain the flexibility and
fluidity of normal pen and paper, but which are structured enough to allow
robust interpretation and processing in the digital world. This paper considers
the design of a class of simple printed templates that allow users to make
common marks in a fluid fashion, and allow additional gestures to be invented
by the users to meet their needs, but at the same time encourages marks that
are quite easy to recognize.